It is known that for wiping glass surfaces which are subjected to rain or splashing, good visibility through the glass surfaces is ensured by the use of oscillating windshield wipers which rub against the swept surfaces with a wiper blade. The wiper blade is generally driven by a windshield wiper arm, which itself is mechanically fixed to a drive unit, generally consisting of an electric motor which communicates oscillating rotary motion through a reduction gear to the wiper arm. For this purpose, the drive unit has a drive spindle on which a drive head is mounted. The drive head is itself coupled to the wiper arm that carries the armature of the wiper blade.
The windshield wiper arm may have to be replaced due to wear or to some mechanical fault. Accordingly, it is usual to fit the drive head on the drive spindle by means of a disengageable fastening member such as a nut, which can be unscrewed so that the wiper arm can be separated from the drive spindle. In the interests of neat appearance, it is necessary that the securing means for the wiper arm should be hidden. In addition, it is desirable to protect this securing means against ingress of foreign matter, for example dirt. It is already known to achieve this by covering the nut with a removable shield, which should preferably be coupled to a shroud portion of the wiper arm in such a way that the shield cannot be lost, that is to say the shield should be able to be moved away from the coupling between the wiper arm and the output spindle so that the windshield wiper arm can if necessary be changed.
French published patent application FR 2 462 311A discloses an arrangement in which a shield is attached to a shroud through trunnions which are carried by the shield, and which are inserted in grooves provided in the shroud, in such a way that the shield can both pivot about the trunnions and be displaced by sliding movement along grooves formed in the shroud. With that arrangement, the shield which initially surrounds the drive head is first pivoted and then moved backwards, that is to say towards the wiper blade, so that access to the nut that secures the drive head on the drive spindle is obtained.
It has become apparent that the trunnions are quite fragile, so that they are liable to become damaged due to mishandling, thus necessitating the replacement of the entire arm. In addition, the cost of manufacture of such an assembly is quite high, having regard to the fact that it is necessary to form slideways in the shroud, the latter usually being made of sheet steel.